Apparatus for examining threads visually for defects



April 1952 y JEAN-PAUL LAETSCH ETAL 2,592,039

APPARATUS F OR EXAMINING THREADS VISUALLY FOR DEFECTS Filed Sept. 4,1947 r 2 SI-IEETfi-SI-IEET 1 INVENTORS. fi e ha Lae'fse/l BY pal/l LhfyI A QWZM JEAN-PAUL LAETSCH ET AL- 2,592,039

April 8, 1952 APPARATUS FOR EXAMINING THREADS VISUALLY FOR DEFECTS 2SHEETSSHEET 2 Filed Sept. 4, 1947 INVENTOR. deamPau/ Laelirc z -BY PaulLiT/j mm MW Patented Apr. 8, 1952 OFFICE APPARATUS FOR EXAMINING THREADSVISUALLY FOR DEFECTS Jean Paul Laetsch, Zurich, Switzerland, and PaulLitty, Guebwiller, France Application September 4, 1947, Serial N o. 772,190 In France September 9, 1946 9 Claims This invention relates to thevisual examination or checking of threads and aims to provide animproved apparatus whereby threads can be examined visually in acontinuous manner in order to reveal irregularities, the shaggy state,impurities or other defects.

One object of the invention is to provide means whereby the visualexamination of threads may be carried out in a more efiicacious andconvenient manner than hitherto.

Further objects and features of the invention will appear in thefollowing specification and be pointed out in the claims, whilst othersmay be obvious to those versed in the art.

. For the visual examination of threads it has been a common practice towind the thread in parallel spirals on plates or cartons. A carton,serving as a screen, was chosen of such a colour that it contrasted withthe thread which was wound thereon in such a way as to facilitatechecking, by synoptic comparison of consecutive spirals disposed at anappropriate distance from one another.

Extremely influenced I by changing lighting conditions of thesurroundings, this method only allowed an incomplete examination ofthreads whatever might be the orientation that could be brought to begiven to the wound carton with respect to the light. Moreover, the sideof the threads applied against the winding carton always remainedinvisible to the eye. Besides, the examination was limited to the partof thread wound on the screen.

The present invention aims to overcome the diificulties, and is based inpart upon a clear appreciation of the desiderata, and on the ways ofachieving the latter hereinafter set forth.

To obtain an efficacious checking of the thread, it has now been found.necessary for it to be possible to examine it in optimum conditions oflighting, independent of all outside influence, over an unlimited lengthand on all its surfaces. It has further been ascertained that to examinea thread in the room, arranged before a screen at a certain distancefrom this latter, the site of the source of light has a great influence.Thus to reveal irregularities such as cuts, bulky threads .or others, ithas been found advantageous to light the thread by rays striking ittransversely, whilst lighting in the longitudinal direction allows ofrecognising the existence of impurities such as husks, knobs and thelike in a manner more practical to the eye of the observer. By givingthe thread a translatory movement, limitless-lengths thereof can beexamined and the examination can be carried-out in a more completemanner than if the thread remains immobile. This translatory movement ispreferably such that two consecutive parallel helices move in oppositedirections.

The practical realisation, either separately, or in combination one withanother, of the different conditions for a proper examination of thethreads is the subject of the present invention.

This contemplates apparatus according to which the thread to be examinedis animated by the aforesaid movements, by means of the suitablearrangement of guiding and drawing parts in a casing artificiallylighted and preferably arranged in a darkened locality.

The annexed diagrammatic drawing, comprising three figures, shows by wayof example, a form of execution of an apparatus by means of which it ispossible to obtain a visual check of the thread with all the desiredprecision and under the most imprdved convenient conditions.

Fig. 1 shows this apparatus in elevation,

Fig. 2 is a side sectional View, and

Fig. 3 is a plan view.

The various members are housed in a casing I, provided at the front withwindow-shutters 2 (Fig. 3) pivoting about an axis 3. Thesewindow-shutters, when closed, leave a free space or viewing opening 4 infront of the screen 5 which is interchangeably mounted, for example inguides 6. The thread to beexamined proceeding from a spool 1, arrangedon a spindle 8, is led over a thread brake or tensioner 9 and a guideIll on to roller H and thence across two pairs of combs l2 and 13 on toand around a second roller M, then back and again around the roller l I,thence forwardly and again around the roller l4, etc., until thereexists in front of the screen 5 a plurality of parallel rows of threads.The roller I4 is driven from a driving shaft l5 by means of intermeshinggears I6 and H. The outgoing thread is passed across the thread-guide I8and is coiled on a spool IQ of which the rotation is ensured simply bypressure on cylinder 20 of the driving shaft [5. The spool I9 is mountedfor reciprocating movement in the direction of its axis for whichpurpose said spool is carried by a rod 23 which is provided with twofingers 22 between which is received a pin or spur 2| carried by arotary disk 24, the latter having worm teeth which mesh with a worm 25on the driving shaft 15.

The driving of the shaft l5 can be effected, either by hand by means ofa crank not shown in the drawing, or by an electric motor connected forexample by a belt to the pulley 26. The drive may be continuous orintermittent. The speed of passage of the thread in front of the screencan be regulated in known conditions, by means of a rheostat forexample.

Between the pairs of combs l2 and I3, the thread bears on smooth bars 21preferably of glass. The teeth of the comb l3 are staggered in relationto those of the comb l2 to compel the thread to bear always on the sameside of the teeth and thus ensure a perfect parallelism of the variousrows of thread between them.

Between the combs I3 the rows of thread are freely suspended, the screenbeing the background. It results from this arrangement that the thread,under the influence of its own torsion, turns more or less about itsaxis, thus exhibiting its various surfaces to the observer.

The combs l2 and I3 ensuring parallelism of the various rows of threadsbetween them, as well as the bars 21, or the rollers l l and I4, couldbe replaced, either by channelled rollers or rollers with ribs orswellings, or by guide pulleys or in any other useful manner. It ispreferable to give the adjacent rows of thread a translatory movement inopposite directions and for this purpose the thread, after leaving theguide It, is led through the two sets of combs l2, l3 and then aroundthe roller l4 and back through the two sets of combs and around theroller H, and thence again through the two sets of combs and around theroller I4, etc. With this manner of threading up the device, eachstretch or length of thread between the two pairs of combs and which issituated in front of the screen 5, is travelling in a direction oppositeto that of the adjacent thread.

Another Way of threading up the device would be to lead the threadaround the roller 14 and then back of the screen 5 and around the roller1 I, and then pass the thread through the combs l2 and I3 and around theroller I 4 again and then lead the thread to the roller ll back of thescreen, etc. With this manner of threading up the device all of thethread sections in front of the screen will be travelling in the samedirection.

To facilitate threading of the device the combs 13 are shown as beingpivotally mounted in their supports so that they can be turned into theposition shown by dotted lines l3 in Fig. 3. Furthermore, the support 40for the guiding system ll, I2, l3, I4, 21, is pivotally mounted onsupporting brackets 4| as shown at 29, thereby permitting the assemblyto be turned in the direction of the arrow C from its operative verticalposition shown in full lines Fig. 2 into an inclined position shown indotted lines.

When a spool is exhausted or is replaced by another, the work ofthreading can be dispensed with, if care has been taken to attach thethread from one spool to another.

The turning down of the comb l3 can be effected by acting on the knob 30in such a manner as to disengage a retaining cog urged by a spring 3|,which also serves to keep the comb I3 in a staggered position withrespect to the comb [2.

The lighting of the thread passing before the screen 5 is ensured by twosources of illumination 32, arranged on either side of the field ofexamination and rendered invisible to the observer by means of thewindow-shutters 2.

A clapper or shield 34, controlled from a distance and pivoting about anaxis 33 of a fixed wall 35, allows of illuminating the thread to beexamined, either directly in the longitudinal direction, or indirectlyin an inclined transverse direction. In the first case, supposing theclapper 34 is in the full line position Fig. 3, the light rays Remanating from the source 32, sweep the threads in the direction oftheir axes or length as indicated by the arrows R. In the case theclapper is in the dotted line position 34 the light rays R are directedtowards the interior surface of the window shutter 2 and reflected inthe direction R" onto the surface of the field of examination at anangle to the axes or longitudinal direction of the threads.

It is noted that, in the two cases, the background screen 5 forms acontrast with the thread bathed in light. In the case of the directillumination the rays R do not reach the screen, this latter remainingdark, owing to the walls 36 which prevent their passage.

According to whether it be desired to obtain more or less markedcontrasts, use can be made of screens of various colours.

The installation above described presents a single field of examination.It is possible, in the same casing, to superpose several fields ofexamination in such a manner as to be able to control simultaneously thethread from several spools. Mere duplication or multiplication of partsfor dealing with several threads instead of a single one, is notexcluded by the claims referring more especially to the simpler formillustrated by way of example.

It will be obvious to those versed in the art that the invention issusceptible of various changes in the shape, construction and means ofsupport of its various elements wtihout departing from the scope andspirit of the appended claims.

We claim:

1. Visual thread examining apparatus comrising the combination of acasing with a viewing opening at the front, a screen mounted in saidcasing, thread feeding, supporting and guidirig means within said casingleading said thread in a continuous manner in parallel rows in front ofsaid screen, sources of light mounted within and at each side of saidcasing, moveable clappers operable at will into two positions, saidclappers in one position allowing direct light rays from said sources inthe longitudinal direction of the parallel rows of thread to illuminatethem directly endwise, whilst intercepting rays which in the otherposition of said clappers give frontal illumination of the thread byreflection from interior front surfaces in the casing.

2. Visual thread examining apparatus comprising the combination of acasing, windowshutters forming the front of said casing and leaving aviewing opening, a screen interchangeably mounted in said casing, threadfeeding, supporting and guiding means within said casing leading saidthread in a continuous manner in parallel rows in front of said screen,sources of light disposed in said casing and means controlling the lightrays emanating therefrom to cause illumination of the rows of thread inthe field of examination selectively at will either in the direction oftheir axes or in a direction at an angle thereto, the thread in parallelrows before the screen having controllable translator-y movement andbeing so associated with appropriate guiding members of the threadfeeding system that the various parallel rows are so propelled that twoconsecutive rows move in opposite directions.

3. Visual thread 'e'xamining apparatus comprising th combination of acasing, windowshutters forming the front of said casing and leaving aviewing opening, a screen interchangeably mounted in said casing, threadfeeding, supporting and guiding means within said casing leading saidthread in a continuous manner in parallel rows in front of said screen,sources of light disposed in "said casing and means controlling thelight rays-emanating therefrom to cause illumination of the rows ofthread in the field of examination selectively at will either in thedirection of their axes or in a direction at an angle thereto, thethread in parallel rows before the screen having controllabletranslatory movement and being so associated with appropriate guidingmembers of the thread feeding system that the various parallel rows areso propelled that each row is displaced in an opposite direction to thatin which an adjacent row is displaced.

4. Visual thread examining apparatus comprising the combination of acasing, windowshutters forming the front of said casin nd leaving aviewing opening, a screen interchangeably mounted in said casing, threadfeeding, supporting and guiding means within said casing leading saidthread in a continuous manner in parallel rows in front of said screen,Sources of light disposed in said casing and means controlling the lightrays emanating therefrom to illuminate the rows of thread in the fieldof examination before said screen selectively at will either in thedirection of their axes or at an angle thereto, the rows of thread beingmaintained rigorously parallel by said guiding means comprising guidesin the form of two groups of combs disposed respectively at the entranceand exit of the observation field, the combs in each of these groupsbeing staggered with respect to one another constraining the thread tobear constantly on the same side of the comb teeth.

5. Visual thread examining apparatus as in claim 4, wherein one of thecombs of each group is mounted to be lowerable from the net of the rowsof thread thereby facilitating threading the latter.

6. In visual thread examining apparatus, the combination with a casinghaving a viewing opening, of a screen mounted in said casing in positionto be viewed through said opening, thread feeding, supporting andguiding means having provision for holding a continuous length of threadin parallel rows between said screen and opening and for feeding saidthread forwardly, a source of light mounted within the casing andpositioned to direct light on to the rows of threads in the direction oftheir length, a reflector positioned to reflect light from said sourceof light frontally on to the rows of threads, a shield movable at thewill of the operator into either one of two positions, in one of whichpositions it cuts off from the reflector the light from the source oflight while permitting light from said source to illuminate the rows ofthreads in the direction of their length, and in the-other of whichpositions it intercepts the light projected from the source of light inthe direction of the length of the threads while permitting projectionof light from the source of light on to the reflector which reflects thelight on to said rows of threads from the front, whereby the thread maybe examined through the viewing opening under optimum lightingconditions and without any exterior illumination.

of thread in parallel rows between said screen and said opening and withthe section of thread forming each row supported at its ends only andbeing. freely suspended between said ends, said means feeding the threadin the direction of its length, a source of light within the casing ateach side of said opening and positioned to project light on to the rowsof thread in the direction of their length, a reflector at each side ofsaid opening to reflect light from the corresponding light sourcefrontally on to the rows of threads, a shield at each side of theopening movable at the will of the operator into either one of twopositions, in one of which positions it cuts off from the correspondingreflector the light from the corresponding source of light whilepermitting light from said source to illuminate the rows of threads inthe direction of their length and in the other of which positions itintercepts the light projected from the corresponding light source inthe direction of the length of the rows of threads while permittingprojection of light from said source on to the corresponding reflectorwhich reflects the light on to the rows of threads from the front,whereby the thread may be examined throu h the viewing opening underoptimum lighting conditions and without any exterior illumination.

8. Visual thread examining apparatus comprising a casing, twowindow-shutters forming the front of the casing and spaced apart to formbetween them a viewing opening, a screen within the casing in positionto be seen through the viewing opening, thread feeding, supporting andguiding means having provision for holding a continuous length of threadin parallel rows between said screen and said opening and for feedingsaid thread forwardly, a source of light within the casing at each sideof said opening and positioned to project light on to the rows of threadin the direction of their length, the inner face of each window-shutterconstituting a reflector to reflect light from the corresponding sourceof light on to the rows of threads from the front, a shield at each sideof the viewing opening movable at the will of the operator into eitherone of two positions, in one of which positions it cuts off from thereflecting surface of the correspondin window-shutter the light from thecorresponding source of light While permitting light from said source toilluminate the rows of threads in the direction of their length, and inthe other of which positions it intercepts the light projected from thecorresponding light source in the direction of the length of the rows ofthreads while permitting projection of light from said source on to thereflecting surface of the corresponding window-shutter, which surfacereflects the light on to the rows of thread from the front.

9. Visual thread examining apparatus of the character describedcomprisin a casing having a viewing opening, a screen within said casingin position to be viewed through said viewing opening, thread guidingand supporting members for supporting the thread in front of the screenin horizontal parallel rows arranged in a vertical plane, supportingbrackets within the casing above the thread guiding and supportingmembers, and means for pivotally suspending the thread guiding andsupporting members Irom UNITED STATES PATENTS said brackets, wherebysaid thread guiding and supporting members can be swung forwardly NumberName Date about their pivotal support to facilitate the J H h: 1924threading operation, 5 1,721 8 lhzham uly 23, 9 JEAN PAUL LAETSCH;1,930,077 Bentley Oct. 10, 1933 PAUL LITTY 2,105,715 Birch Jan. 18, 19382,376,773 May 22, 1945 REFERENCES CITED 2,412,381 Dec. 10, 1946 Thefollowing references are 0! record in the W file of this patent:

